This application is based on and incorporates herein by reference Japanese Patent Application No. 11-357193 filed on Dec. 16, 1999.
The present invention relates to an adjustment method and system for adjusting temperature characteristics in a position measurement sensor having a non-contact type measurement element for measuring a position of a rotatable body as well as for adjusting temperature characteristics in an electronic control unit that is fed with an output of the position measurement sensor. For instance, such a method and system can be used to adjust temperature characteristics of a control value in a throttle valve position sensor having a non-contact type measurement element (e.g., a Hall element, a Hall IC or the like) for measuring a rotational angle of a throttle valve that adjusts the amount of intake air supplied to an internal combustion engine as well as to adjust temperature characteristics of control values in an electronic control unit provided for controlling the internal combustion engine.
Exemplary prior art publications relevant to the method and system for adjusting the temperature characteristics of the position measurement sensor include Japanese Unexamined Patent Publication No. 48-48087 and Japanese Unexamined Patent Publication No. 2-168181.
The former publication discloses a magnetic sensor having a magneto-resistive element that is connected in series with a diode to temperature-compensate an output voltage of the magnetic sensor. The latter publication discloses a magnetic sensor having a magneto-resistive element. This sensor is supplied with a power supply voltage that has been adjusted for changes in ambient temperature by a positive characteristics temperature sensitive resistive element (positive characteristics thermistor) and a fixed resistor. With this arrangement, an output voltage of the magnetic sensor is temperature-compensated.
To compensate for the influence of the changes in the ambient temperature on the sensor output, the magneto-resistive element of the magnetic sensor is connected in series with the diode in the former publication, and the magneto-resistive element of the magnetic sensor is connected in parallel with the positive characteristics temperature sensitive resistive element in the latter publication.
In both the prior art magnetic sensors, if a large change in ambient temperature occurs at a predetermined level, the sensor output can probably be compensated in consistent with the changes in the ambient temperature. However, for example, if a rotational angle of a rotatable body (e.g., a throttle valve of a vehicle) is to be measured, the above elements, which show constant temperature characteristics, are not sufficient to provide appropriate temperature-compensation. This is due to the fact that an ambient temperature around the sensor, an electric motor for rotating the rotatable body or the like varies depending on its location within the vehicle and also depending on changes in operating condition of the vehicle (i.e., changes in operating condition of the vehicle before, during or after driving the vehicle).
The present invention addresses the described disadvantages. Therefore, it is an objective of the present invention to provide a method and system for appropriately adjusting temperature characteristics of a position measurement sensor having a non-contact type measurement element for measuring a position of a movable body as well as for appropriately adjusting temperature characteristics of various control values computed in an electronic control unit that is fed with an output of the position measurement sensor.
To achieve the objective of the present invention, there is provided an adjustment method and system. The position measurement sensor used in the method and system has a non-contact type measurement element including a position measurement unit for measuring a position of a movable body. The measurement element further includes a temperature measurement unit integrated therein for continuously measuring an ambient temperature around the measurement element and also includes an output terminal for outputting a position value of the movable body measured by said position measurement unit as well as a temperature monitor terminal for outputting an ambient temperature value measured by the temperature measurement unit. The position value outputted from the output terminal and the ambient temperature value outputted from the temperature monitor terminal are inputted to an externally connected electronic control unit, wherein various control values computed in the electronic control unit are adjusted based on the ambient temperature value outputted from the temperature monitor terminal.
The measurement element can also include a compensation circuit, wherein a position value of the movable body measured by the position measurement unit is temperature compensated in the compensation circuit based on the ambient temperature value measured by the temperature measurement unit before outputting the position value of the movable body to the electronic control unit.